<!DOCTYPE html>
<!--文档头声明，让浏览器知道以什么标准写的以下代码-->
<html>
         <head>
               <meta charset="utf-8">
                <title>border</title>
              
                <style>
                    div{width:0px; height:0px; 
                    /*background: yellow url(img/pika.jpg) center no-repeat;*/
                    /*border: 20px solid red;*/

                    /*写法一: 每条边框的宽度/样式/颜色全部分开写*/
                   /* border-top-width: 20px;
                    border-right-width: 100px;
                    border-bottom-width: 50px;
                    border-left-width:20px;
                    border-style: solid;
                    border-color: red;*/
                      
                   /*写法二: 每条边框的复合写法*/
                    /*border-top: 20px solid greenyellow;
                    border-right: 40px dashed pink;
                    border-bottom: 50px solid yellow;
                    border-bottom: 40px dotted palegreen;*/
                    
                    /*利用Border制作有趣的效果:*/
                    border-top: 100px solid grey;
                    border-right: 100px solid transparent;
                    border-bottom: 100px solid grey;
                    border-left: 100px solid grey;
                    
                    border-radius: 50%;
                  }
                </style>
         </head>
          <body>
          	<div> 
       
          	</div>
          	
                
          </body>
</html>